PHARYNGEAL SWALLOWING - THE MAJOR FACTOR IN CLEARANCE OF ESOPHAGEAL REFLUX EPISODES

Objective This study defined the clearance mechanisms of naturally occ urring reflux episodes in normal subjects and patients with gastroesop hageal reflux disease. Summary Background Previous studies on acid cle arance have been performed in the laboratory setting in supine subject s using acid instillation and stationary motility. The mechanisms of c learance have not been studied using ambulatory pH and motility monito ring. Methods A new system capable of monitoring simultaneously for 24 hours pharyngeal pressure, esophageal motility, and pH was used to st udy the clearance of naturally occurring reflux episodes in 10 normal subjects and 18 patients with gastroesophageal reflux disease. Esophag eal contraction waves were classified as primary (i.e., initiated by a pharyngeal swallow) and secondary (i.e., unrelated to a pharyngeal sw allow). Results A total of 1288 reflux episodes were analyzed, during which 2781 contraction waves occurred. Clearance (i.e., restoration of pH to > 4) occurred after primary peristalsis in 83% of reflux episod es. An additional 11% were cleared by pharyngeal swallows without an e sophageal body response. Secondary waves were rare and when they occur red, only 19% were peristaltic. Secondary peristalsis cleared only 9 o f the 1288 reflux episodes. Patients and normal subjects cleared reflu x episodes similarly. Baseline swallowing frequency was 0.87/min durin g the daytime and increased.to 2.59/min (p < 0.01) during daytime refl ux episodes. Swallowing frequency in response to nighttime reflux epis odes was less (1.42/min; p < 0.05). Conclusions Pharyngeal swallowing is the most important mechanism for esophageal acid clearance. Seconda ry waves are rare, usually disorganized, and unimportant in clearing a reflux episode. During sleep, the mechanisms of clearance are depress ed.